Submission #24476637

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Source Code Expand

import sys
from collections import defaultdict, deque

def main(f):
  N, M = list(map(int, f.readline().split()))
  P = [None] + list(map(int, f.readline().split()))
  link = [[] for _ in range(10**5+1)]
  for _ in range(M):
    x, y = list(map(int, f.readline().split()))
    link[x].append(y)
    link[y].append(x)

  flag = [0] * (N+1)
  q = deque()

  result = 0
  for n in range(1, N+1):
    if flag[n] == 1:
      continue

    group = set()
    ps = set()
    q.append(n)
    while q:
      x = q.pop()
      if flag[x] == 1:
        continue
      group.add(x)
      ps.add(P[x])
      flag[x] = 1
      for y in link[x]:
        q.append(y)

    result += len(group.intersection(ps))
#    for i in group:
#      if P[i] in group:
#        result += 1

  print(result)

main(sys.stdin)

Submission Info

Judge Result